(CBS/WUSA) WASHINGTON – Police say the 19-year-old brother of NFL star Vernon Davis has been charged in the murder of a Denver tourist.

According to CBS affiliate WUSA, police say they charged Michael Davis with first-degree murder on Wednesday for the April 24 bludgeoning of 66-year-old Gary Dederichswith some kind of object, believed to be a claw hammer.

Davis had already been charged in connection with other hammer attacks in the area. According to the Washington Post, Davis was charged April 28 with two counts of assault with intent to kill while armed.

He was arrested after he allegedly attacked a 19-year-old D.C. woman, WUSA reports. Police found a claw hammer in Davis’s bag, a weapon they believe was used in at least two of the attacks.

The Washington Post reports police are investigating five attacks in total.

A defense attorney for Davis reportedly argued there was no probable cause for his arrest because the victims could not credibly identify their attacker. The attorney said one of the victims, whose skull was fractured, was attacked from behind.

The judge overruled the attorney’s argument and said Davis will remain behind bars until his next hearing, according to WUSA.

The Washington Post reports that Davis was held a year ago for psychiatric evaluation when his teachers and guardian became fearful of his behavior, according to court documents.

Davis is the brother of San Francisco 49ers tight end Vernon Davis and Miami Dolphins cornerback Vontae Davis.